C ++函数返回数组 [英] C++ functions returning arrays

问题描述

我是那种新的C ++。我习惯了在Java编程。这种特殊的问题是引起了我很大的问题，因为C ++不是演戏像Java，当它在处理数组。在C ++中，数组只是指针。

I am sort of new to C++. I am used to programming in Java. This particular problem is causing me great issues, because C++ is not acting like Java when it is dealing with Arrays. In C++, arrays are just pointers.

但是为什么这code：

But why does this code:

#include <iostream>
#define SIZE 3
using namespace std;

void printArray(int*, int);
int * getArray();
int ctr = 0;

int main() {
  int * array = getArray();

  cout << endl << "Verifying 2" << endl;
  for (ctr = 0; ctr < SIZE; ctr++)
    cout << array[ctr] << endl;

  printArray(array, SIZE);
  return 0;
}

int * getArray() {
  int a[] = {1, 2, 3};
  cout << endl << "Verifying 1" << endl;
  for (ctr = 0; ctr < SIZE; ctr++)
    cout << a[ctr] << endl;
  return a;
}

void printArray(int array[], int sizer) {
  cout << endl << "Verifying 3" << endl;
  int ctr = 0;
  for (ctr = 0; ctr < sizer; ctr++) {
    cout << array[ctr] << endl;
  }
}

打印出校验2和3核实也许这事做与数组作为指针真正处理方式。任意值

print out arbitrary values for verify 2 and verify 3. Perhaps this has something to do with the way arrays are really handled as pointers.

推荐答案

由于您的阵列堆栈中分配。移动从Java到C ++，你必须非常小心对象的生命周期。在Java中，一切都是堆中分配，当对它的引用仍然是垃圾回收。

Because your array is stack allocated. Moving from Java to C++, you have to be very careful about the lifetime of objects. In Java, everything is heap allocated and is garbage collected when no references to it remain.

然而在这里，你定义一个堆栈中分配数组，当你退出功能其中的getArray被销毁。这是的（很多）的原因矢量preferred平淡阵列一 - 。他们处理的分配和释放你

Here however, you define a stack allocated array a, which is destroyed when you exit the function getArray. This is one of the (many) reasons vectors are preferred to plain arrays - they handle allocation and deallocation for you.

#include <vector>

std::vector<int> getArray() 
{
    std::vector<int> a = {1, 2, 3};
    return a;
}

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